Kate Winslet broke Tom Cruise's underwater filming record from Mission: Impossible - Rogue Nation (2015) of six minutes with a record of seven minutes and 15 seconds.
According to James Cameron, the Avatar sequels were such a massive undertaking that he divided the four scripts between the writing team of Rick Jaffa, Amanda Silver, Josh Friedman, and Shane Salerno. Cameron delves further explaining the story process: "I think we met for seven months and we whiteboarded out every scene in every film together, and I didn't assign each writer which film they were going to work on until the last day. I knew if I assigned them their scripts ahead of time, they'd tune out every time we were talking about the other movie."
Sigourney Weaver trained in breath-holding to shoot the film's aquatic motion-capture sequences. She also joined her younger co-stars in learning underwater sign language and parkour, for scenes of Na'vi teens running along tree boughs or racing to the tops of floating mountains. "I was determined to be able to do everything they did. I didn't want anyone to say, 'She's kind of an old lady,'" Weaver says. "We all had to be really fit, and parkour is a very good way of getting there." Other cast members participated in knife-fighting and archery lessons, but "Kiri is not a fighter," Weaver adds. "She's a very gentle person. She can be filled with rage, and she's very sensitive to injustice and cruelty, but she doesn't use weapons. She has other powers."
Not only did James Cameron shoot two full Avatar sequels at once, but he also waited to start filming until all the scripts for Avatar 2, Avatar 3, Avatar 4 and Avatar 5 were complete. He told Collider that his model was similar to what Sir Peter Jackson did with "The Lord of the Rings" trilogy. He explained, "They took that chance to launch on all three of those films, but he had the books mapped out, so he could always show the actors what they needed to know about their character arc. So I felt I had to do the same thing. I had to play this as if the books already existed. So the only way for us to do that was to write all the scripts and let the actors read all the scripts and see where their characters were going and what it all meant. Not that that's actable in the moment, but I think it's something that the actors could work into their preparation for their characters."
James Cameron: voice on the ship when Quaritch first wakes up. ''Stand by. Two minutes to Pandora insertion. Secure for Delta V.''